They saw what Israel, and American, did to Iraq, and realize they have
no choice but to fight. The danger here is their only defense is nukes,
they can fight a conventional war, but once they annihilate the Fifth
Fleet than Americans will turn to nukes.
You can rest assured that Iran has gotten some nukes out of Russia or
Pakistan. I just don't picture them letting America attack and going
through an Israeli occupation like Iraq. Living with Death Squads, and
seeing their wives and children blown up in marketplaces with Mossad
bombs.
Iran will fight, they have no choice.